church of skintology is facing a prospect of a major tell-all book. The author -- actress leah remini. Perhaps the most famous person ever to publicly split with the church. Tonight what remini is saying and how the church is reacting. On the hit cbs sitcom, "the king of queens," leah remini is displaying a similar toughness, speaking here with access hollywood. I'm good. I have my family. My real friends are behind me and I think that says a lot. Reporter: Today, the news that she's writing a tell-all memoir. Remini says to "us weekly" -- it will include my experiences, everything that's taboo to talk about. Reporter: She will have a lot of experience to draw upon. She joined the church at age 7, briefly served as a member of the elite religious order know as sea org., And then, as a celebrity, moved among scientology's most famous members. Remini's sister nicole, herself a former scientologist, says leah's relationship with the church began to sour in 2006, at the wedding of tom cruise and katie holmes, where leah reportedly asked the head of the church, david miscavige, where his wife was. Miscavige's wife, shelly, has not been seen publicly in many years. In a radio interview, remini said her sister was rebuked by church officials for asking about this. She was totally shocked, she didn't -- she did not at all expect that type of response. And then it just kind of escalated from there. Reporter: The church has publicly denied the story about remini confronting david miscavige at tom cruise's wedding. As for those reports about shelly miscavige, the church released a statement to abc news saying -- mrs. Miscavige continues her work in the church as she always has." Remini is perhaps the highest profile departure since paul haggis, the screenwriter of "crash' and "million dollar baby." This week, haggis released an open letter praising remini's brave decision and thanking he for being one of the few scientologists to defend him when he left. In a statement to abc news the church called haggis a status-obsessed screen writer who is, quote, exploiting his tenuous connection with scientology to grab head lines end quote.

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